Lamp fuse protector



Dec. 6, 1938- w. E. ANDERSON ET AL 2,139,252

LAMP FUSE PROTECTOR Filed May 27, 19256 ATTORI EY Patented Dec. 6, 1938UNITED n STATES PATENT; ori-lcs LAM? FUSE PROTECTOR Application May 27,1936, Serial No. 81,994

6 Claims.

This invention relates to incandescent electric lamps or the like andmore particularly to lamps in which a fuse constitutes part of a leadwire.

It is the practice in certain types of incandescent electric lamps,particularly high-wattage lamps, to provide one of the lead wires with afuse. The fuse is provided for the reason that in some cases the burningout of the filament of an incandescent electric lamp causes an arc toform therein which may result in the bursting of the bulb and theblowing of the fuse in the main line. In some cases, the arc travelsdown the lead wires of the lamp and into the base and socket before themain fuse opens the circuit, causing considerable damage.

In practice it has been found desirable, therefore, to place a fuse inthat portion of the lead wire extending from the stem press to the lampbase. It sometimes happens, however, that when the fuse melts themetallic vapor sets up a conductive path and an 'arc starts between theleads.

The present invention provides a fuse with a protective housing whichserves'to prevent the formation of an arc between the leads. It isnecessary, however, to enclose completely the lead wire in which thefuse is incorporated, and for this purpose a tubular insulatve coveringis provided. The tubular covering or housing is of such character as tobe adjustable as to length to meet certain variations in the dimensionswhich vary in different lamps, as will hereinafter be more fullydescribed.

In copending application Serial No. 82,021, led May 27, 1936, andassigned to the present assignee,

a lamp fuse housing of exible material to meet varying dimensions isprovided. The present invention provides a rigid member, preferably aglass tube, which is held in place by means cooperating with the lampbase and which may be adjusted by a slight movement relative to theholding means.

An object of the present invention, therefore, is to provide a lamp fusewith a closed chamber to prevent arcing between the leads by reason ofthe conductive path resulting from the metallic vapor formed when a fusemelts.

Another object of the invention is to provide a simple form of fusehousing which may be held in position surrounding the lead wire in whichthe fuse is incorporated and which may be adjusted as to length.

A further object of the invention is to provide a fuse housing supportedby an insulative wall' which serves as a barrier against the formationtheir relative positions.

of an arc between the lower part of the fuse lead and the other lead orbase shell of the lamp.

Other objects and advantages will be more clearly understood byreference to the following description together with the accompanyingdrawing in which:

Figure 1 shows an incandescent electric lamp partly in section with thepresent invention applied thereto and Fig. 2 is'a view taken on lineII-II in Fig. 1. 'I'he present invention may 'be applied to a lampincluding a bulb I0, having the usual flare tube II sealed at I2 to thebulb neck I3. The flare tube extends into the bulb and is provided witha press I4 through which lead wires I5 and I6 extend. One end of leadwire I6 is connected at I1 to the metallic shell I8 of a base I9 whichbase is attached to they bulb neck by cement 2 I. The other end of thelead wire I6 extends into the bulb and is connected to a support wire 22which in turn is connected to one terminal of a filament 23. The otherterminal of the filament is connected to'one end of a support wire 24,the other end of which is connected to one end oi lead Wire I5. The leadwire I5 extends to the center contact 25 of the base I 9 and is ofreduced diameter to serve as a fuse 20.

Surrounding the i'use is a tubular housing 26, preferably in the form ofa glass tube, but it may be of any suitable insulative material. In thebase I9 is disposed a disk 21 of any suitable material, such asasbestos, provided with an aperture 28 to receive one end 29 of the tube26 which surrounds the fuse 20. The other end of the tube extends up toand contacts with the press I4.

The end 29 of the tube 26 tightly, butslidably, fits the aperture 28. Asthe base is applied, the upper end or the tube is brought into contactrwith the press, and as the base is forced into position, the tube 26will move into the aperture 28 to accommodate any variation in dimensionresulting from variations-in the dimensions of the parts.

The tubular casing, in the present embodiment, surrounds the fuse lead,and provides a substantially closed chamber.

It will be understood that lamps of the charac-v ter to which thepresent invention relates are made at a high rate of speed and certainvariations occur in the dimensions of the parts and in For example,distance X indicated on the drawing may vary by reason of the positionof the press with relation to the bulb neck or the diameter of the bulbneck may vary, thus changing the position of the base with respect tothe iiare tube. On the other hand, the length of the flare tube mayvary.

When applying the present tubular housing, the disk Z1 is forced intothe bottom of the base, and the end 29 of the tube 26 is thrust into theaperture 28. The lead wire with the fuse is then threaded through thetube and the base is applied in the usual manner. As the base is movedto position against the bulb neck, the upper end of the tube is engagedby the under side of the press I4 and, as the bulb and base are movedtogether, the tube can be forced further into aperture 28, thusproviding for a variation in the effective length of the tube toaccommodate variations n the distance indicated by the referencecharacter X.

Although a preferred embodiment of the invention is shown and describedherein, it is to be understood that modifications may be made thereinwithout departing from the spirit and scope oi the invention as setforth in the appended claims.

We claim:

1. A vacuum device comprising a bulb, a ilare tube having a press andsealed to the bulb neck, a base secured to said neck, a lead wire insaid tube, a fuse in a portion of said lead wire, said lead Wireextending in said flare tube to said base, a tubular housing for saidlead wire extending from press to base, held at one end by said aretube, and means carried by said base for supporting the other end ofsaid housing.

2. A vacuum device comprising a bulb, a dare tube sealed to the bulbneck, a base secured to said neck, a lead wire, a fuse in a portion ofsaid lead wire, said lead wire extending from said flare tube to saidbase, a tubular housing for said lead wire, and a disk in said basehaving an aperture to receive one end of said housing.

3. A vacuum device comprising a bulb, a flare tube sealed to the bulbneck, a base secured to said neck, a lead wire, a fuse in ,a portion ofsaid lead wire, said lead wire extending from said flare tube to saidbase, a tubular housing for said lead wire, and a disk in said base,said disk having an aperture slidably receiving one end of said housing,whereby said housing may be adjusted longitudinally and held in anadjusted position.

4. A base for a vacuum device comprising a tubular housing for enclosinga lead wire, a disk secured in said-base, and means for adjustablysupporting said housing on said disk.

5. A base for a vacuum device comprising a tubular housing for enclosinga lead wire, a disk secured in said base, said disk having an apertureto receive one end of said housing to support said housing foradjustment relative to said disk.

6. A b ase for a vacuum device comprising an open-ended tubular housing,a fuse Wire therein with its ends extending beyond said housing, andapertured means in said base for supporting and slidably receiving oneend of said housing.

WALDEMAR E. ANDERSON. JOHN A. LINDER.

